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Letter 3254

Darwin, C. R. to Lyell, Charles

[15 Sept 1861]

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    Discusses CL's correspondence with T. F. Jamieson. Comments on Jamieson's theory that the roads of Glen Roy were formed by a glacial lake. Discusses elevation of Scotland during the glacial period.

Transcription

Down. | Bromley. | Kent. S.E.

Sunday Evening

My dear Lyell

Many thanks for sending me your most interesting correspondence. What a capital man, Jamieson is! The letters came this morning & shall be forwarded tomorrow, which is the same as if posted by London Monday general post. I could not read them this morning for I was in middle of experiments on Dionæa, which could not be stopped.

It is a grand subject you are discussing, & light must soon appear.— I wish I could help in the least, but I cannot. The absence of deltas on upper level of the Lochaber shelves seems to me quite sufficiently accounted for by small amount of land above the shelves on the lake or sea theory. Your argument of if submergence 1200 ft. in Perthshire since chief glacialisation, how about Glen Roy, is very striking. I have just been glancing at my Glen Roy paper; & there yet seem to me several points of very difficult explanation. (1) The levelled land-straits with terrace-like fringes above the level of the highest shelf. (2) the beds of pebbles on very gently inclined surface between Glen Turret & Glen Gluoy; & beds of pebbles on former islet (Meal Roy or Mealderry) at level of Lower shelf at the mouth of Glen Roy. When one sees what little power Glacial sea has to form pebbles, the case seems very odd in Glacial lake. (3) The fringe of detritus on sides of Spean & Roy valleys, about 60 ft thick all down the valley.; and buttresses of gravel on sides of Hills.— Is it possible that the river when it began to flow over the embankment of ice would cut its channel so slow & so drain the lake so slowly as to allow of all this great sloping accumulation? I remember perfectly well my surprise at vast contrast of state of valleys in N. Wales & Lochaber. But I suppose ice-lakes must be true cause.

What Jamieson says about climate not being icy if Scotland &c &c were all submerged 2000 or 3000 ft goes for nothing, when one thinks of Georgia in S. watery Hemisphere.— In former letter you speak of Scotland having been perhaps much loftier so as to account for great glaciers; this rubs against my notions, owing to the great extension & prevalence of Glacial phenomena. It always seems to me, until the contrary can be shown, to be safest to look at the great Glacial period as simultaneous.—

My dear Lyell | Yours most truly | C. Darwin

You quote Heer; I suppose that you know that Wollaston has overly bad opinion (all told me when at Torquay) of his Entomology & declares he is not to be at all trusted; & that Lowe says he has made great mistakes about Madeiran fossil plants.—

    Footnotes Add

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    f1 3254.f1
    The date is given by the relationship to Lyell's letter to Thomas Francis Jamieson, 14 September 1861 (see Wilson ed. 1970, p. 523). The following Sunday was 15 September.
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    f2 3254.f2
    Lyell had apparently sent CD Jamieson's letter of 11 September 1861 (see Correspondence vol. 9, Appendix IX) as well as Lyell's response, of which only the draft is extant (see n. 1, above). Lyell, Jamieson, and CD had been conducting a three-way correspondence for several months concerning the geological interpretation of the `parallel roads' of Glen Roy in Scotland.
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    f3 3254.f3
    See letter to Daniel Oliver, 11 September [1861].
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    f4 3254.f4
    This point is discussed in the draft of Lyell's letter to Jamieson, 14 September 1861 (see Correspondence vol. 9, Appendix IX). Lyell was in the process of revising the discussion of Glen Roy for a new edition of his Elements of geology. In the event, he introduced this discussion in his study of the geological evidences for the antiquity of man (C. Lyell 1863). By arguing for an initial submergence of the highlands of Perthshire, he was attempting to synthesise Jamieson's theory of glaciation with CD's view of submergence and gradual elevation to account for the phenomena of the parallel roads of Glen Roy. Jamieson, however, had pointed out that a major problem with this hypothesis was the absence of marine remains in Glen Roy (see Jamieson's letter to Lyell, 11 September 1861; Correspondence vol. 9, Appendix IX).
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    f5 3254.f5
    `Observations on the parallel roads of Glen Roy, and of other parts of Lochaber in Scotland, with an attempt to prove that they are of marine origin', Philosophical Transactions of the Royal Society of London (1839): pt 1, 39--81 (Collected papers 1: 89--137).
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    f6 3254.f6
    CD studied the glacial phenomena in North Wales in June 1842; he had visited Lochaber in 1838 (see Correspondence vol. 2). For a fuller account of CD's views of the evidence supporting the glacier-lake theory, and his reasons for believing that it failed to explain a number of important points, see Correspondence vol. 4, letters to Charles Lyell, 8 [September 1847] and [11 October 1847], and to the Scotsman, [after 20 September 1847]. For a map of Glen Roy, see p. 248.
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    f7 3254.f7
    See Jamieson's 11 September 1861 letter to Lyell (Correspondence vol. 9, Appendix IX). In his paper on Glen Roy, CD accounted for the erratic boulders of Lochaber by assuming that they had been deposited on beaches or shelves by floating icebergs and subsequently exposed when the sea retreated as a result of the elevation of the land (see Collected papers 1: 121--2). CD described the snow-clad island of South Georgia in the South Atlantic in Journal of researches, p. 273.
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    f8 3254.f8
    Oswald Heer, a specialist on the Tertiary remains of Europe, was currently visiting England at Lyell's request to study the fossil plant remains recently found near Bovey Tracy in Devon (see K. M. Lyell ed. 1881, 2: 346--7, 349--50).
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    f9 3254.f9
    CD had visited the entomologist Thomas Vernon Wollaston in July 1861 during the family's stay in Torquay (see letter to John Lubbock, 1 August [1861]).
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    f10 3254.f10
    Richard Thomas Lowe was an expert on the natural history of Madeira, where he had served as chaplain from 1832 until 1852. Heer, who had made an extended visit to Madeira for health reasons, published a well-known paper on the island's fossil flora (Heer 1857).
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